Bridge to somewhere: Some of the science behind the I-70 bridge repair between Wolcott and Edwards | VailDaily.com

Bridge to somewhere: Some of the science behind the I-70 bridge repair between Wolcott and Edwards

EDWARDS — It was its turn, that's why.

That Interstate 70 bridge between Edwards and Wolcott that has been receiving so much attention was due for a tune-up this summer, said Jason Laabss, project engineer.

"All states do it," Laabs said. "Every state has its own schedule for routine inspections. Those inspections are scheduled years in advance."

The I-70 bridge was not dangerous, and the bridge deck was in great condition, but it did need the attention it's getting, Laabs said.

The Colorado Department of Transportation and Lawrence Construction have been working on the bridge all summer. It's the bridge that spans the Eagle River, U.S. Highway 6 and the Union Pacific Railway line just west of Edwards. The project is located on I-70 between mile points 158.05 and 158.85.

It's time for some attention

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A bridge's turn in line could move up, depending on how old it is and if something extraordinary happens — such as the bridge that was hit by a tractor trailer a couple of years ago. The truck was traveling under the bridge and hit one of the piers, those huge concrete pylons that hold up the bridge.

The bridge did not fall because redundancies were built into the bridge, as they are in most bridges, Laabs said.

"If one part of the bridge fails, the bridge does not come down," Laabs said.

Laabs is a Minnesota native and remembers when one did — the Minneapolis Interstate 35 West bridge that collapsed, Aug. 1, 2007.

CDOT and Lawrence Construction crews are performing preventive maintenance on the 705-foot-long bridge deck and steel girders. Keeping up on routine maintenance can extend a bridge's service life up to 100 years, said CDOT's Tracy Trulove.

This bridge was built in 1970, Laabss said.

Because it's a half-century old, crews are finding and repairing fatigue cracks on the steel girders. You get those over the years with vehicle loading and unloading, like that bridge sees thousands of times each day.

It turns out that fatigue cracks are more likely to occur in steel bridges built between 1950 and 1985. However, due to design advances, bridges built after 1985 are less prone to cracking, CDOT said.

Because this bridge was built in 1970 and is skewed to accommodate crossing Highway 6, the Eagle River and the railroad, it's more susceptible to fatigue cracks, CDOT said.

The cracks they found are minor, but it's important to find them early and upgrade the bridge before it's structurally compromised, CDOT said.

Crossover traffic

The bridge cannot be vibrating while crews are trying to repair those fatigue cracks, so that's why traffic has been diverted off the eastbound bridge and crossed over to two-way traffic on the westbound bridge.

Besides steel and the deck, crews are also replacing bridge expansion joints, asphalt pavement and waterproofing membrane, as well as bridge rail and roadside guardrail. It's all scheduled to be finished this fall.

Two more bridges along I-70 are being repaired in the same way: the Colorado River Bridge near Rifle and the DeBeque overflow bridge on the east end of DeBeque Canyon.